Applications of Non-Rigid Matching to 3D converted-wave (PS) imaging

Abstract

To compensate for lateral or temporal divergence of converted-wave (PS) imaging as a function of azimuth, a two-tiered workflow for applying a non rigid matching (NRM) process is utilized. The resultant product is a final enhanced 3D PS volume with superior stack response and continuity from the optimum combination of two distinct azimuth sectors of a PS prestack time migration (PrSTM) dataset. The method allows for the crossline artifacts from the effect of azimuthal anisotropy on the converted-wave moveout to be almost completely removed. Furthermore, the severe acquisition footprint, from insufficient crossline aperture as a result of a sub-optimum survey design, is effectively mitigated. Seismic data examples of 3D inlines, crosslines and time slices taken from a proprietary 3D/4C OBC survey from the Gulf of Mexico acquired and processed in 2006, demonstrate the compelling benefits of the NRM application and the robustness of the developed workflow. Finally, the output NRM displacement attributes (time-shift values) are found to possess a qualitative value that are not only powerful indicators of azimuthal anisotropy, but also through calibration, may yield valuable information on the magnitude of shear splitting and principal directions of polarization.